System for Coordinating Pressure Pulses and RF Modulation in a Small Volume Confined Process Reactor

ABSTRACT

A plasma processing system for processing semiconductor substrates is provided. The plasma processing system includes a plasma processing volume having a volume less than the processing chamber. The plasma processing volume is defined by a top electrode, a substrate support surface opposing the surface of the top electrode and a plasma confinement structure including at least one outlet port. A conductance control structure is movably disposed proximate to the at least one outlet port and capable of controlling an outlet flow through the at least one outlet port between a first flow rate and a second flow rate. The conductance control structure controls the outlet flow rate and an at least one RF source is modulated and at least one process gas flow rate is modulated corresponding to a selected processing state set by the controller during a plasma process.

CLAIM OF PRIORITY

This application claims priority as a divisional from U.S. patentapplication Ser. No. 14/016,994, filed on Sep. 3, 2013, entitled,SYSTEM, METHOD AND APPARATUS FOR COORDINATING PRESSURE PULSES AND RFMODULATION IN A SMALL VOLUME CONFIDED PROCESS REACTOR, which is hereinincorporated by reference.

FIELD OF THE DISCLOSURE

The present invention relates generally to plasma etch processes, andmore particularly, to methods and systems for controlling plasma etchprocesses

BACKGROUND

Semiconductor device dimensions are pressed to ever smaller dimensionsto enable more devices per wafer with higher performance. Assemiconductor device dimensions become smaller, new challenges arepresented in the process technology needed to form the smaller, moredensely packed devices with high yield. These process requirementsdemand a precise control of plasma chemistry (radical, neutral and ions)to meet both on die as well as across semiconductor wafer etchrequirements.

FIG. 1 is a side view of a simplified schematic drawing of a typicalnarrow gap plasma processing chamber 100. Process gases are injectedthrough a substantially central location 104 of the top portion 108 ofthe plasma processing chamber 100. The process gases are injected intothe plasma processing volume 110 defined as being over the semiconductorwafer 101 to be processed. The semiconductor wafer 101 is supported on awafer support 106.

The process gases flow in a substantially radial direction 112 throughthe plasma processing volume 110 toward a plasma confinement structure114 at the periphery of the plasma processing volume. The process gasesand plasma process byproducts are pumped out at the periphery throughperipheral vents 116 to one or more vacuum pumps 118.

Typical plasma processes are performed at fixed process gas pressure andflow. The fixed process gas pressure and flow often causes radialpressure distributions. By way of example, the pressure P1, P2, P3 ineach respective portion 120, 122, 124, 126 of the plasma processingvolume 110 can vary due to convective flow and other causes.

What is needed is a system, method and apparatus for dynamicallychanging and controlling the peripheral conductance of the process gasesso as to induce a fast change in the pressure in the plasma processingvolume 110.

SUMMARY

Broadly speaking, the present invention fills these needs by providing asystem, method and apparatus for dynamically changing and controllingthe peripheral conductance of the process gases so as to induce a fastchange in the pressure in the plasma processing volume. It should beappreciated that the present invention can be implemented in numerousways, including as a process, an apparatus, a system, computer readablemedia, or a device. Several inventive embodiments of the presentinvention are described below.

One embodiment provides a plasma processing system and method thatincludes a processing chamber, and a plasma processing volume includedtherein. The plasma processing volume having a volume less than theprocessing chamber. The plasma processing volume being defined by a topelectrode, a substrate support surface opposing the surface of the topelectrode and a plasma confinement structure including at least oneoutlet port. A conductance control structure is movably disposedproximate to the at least one outlet port and capable of controlling anoutlet flow through the at least one outlet port between a first flowrate and a second flow rate, wherein the conductance control structurecontrols the outlet flow rate and an at least one RF source is modulatedand at least one process gas flow rate is modulated corresponding to aselected processing state set by the controller during a plasma process.

Another embodiment provides a method of modulating a pressure in-situ ina plasma processing volume of a chamber, the plasma processing volumedefined between a surface of a top electrode, a supporting surface of asubstrate support and an outer region defined by a plasma confinementstructure. The plasma confinement structure including at least oneoutlet port. The method including injecting at least one processing gasinto the plasma processing volume, forming a plasma within the plasmaprocessing volume and modulating a pressure and an RF signal applied tothe plasma processing volume during a period of time when the plasma isformed in the plasma processing volume. The modulating of the pressurebeing controlled by at least one of a first outlet flow out of theplasma processing volume from the at least one outlet port, the firstoutlet flow being a restricted flow path out of the at least one outletport, or a second outlet flow out of the plasma processing volume fromthe at least one outlet port, the second outlet flow being greater thanthe first outlet flow, wherein the second outlet flow being through aless restricted flow path out of the at least one outlet port than thefirst outlet flow.

Yet another embodiment provides a chamber, including a substratesupport, a top electrode, a confinement structure disposed to surroundthe substrate support, such that a plasma processing volume is definedbetween the substrate support, the top electrode and the confinementstructure. At least one RF source coupled to at least one of the topelectrode and the substrate support. The confinement structure includesmultiple outlet ports that surround the substrate support. A conductancecontrol structure is disposed outside of the plasma processing volumeand proximate to the outlet ports, the conductance control structurehaving a positioning actuator that provides movement of the conductancecontrol structure between a first position and a second position, thefirst position placing the conductance control structure immediatelyadjacent to the plurality of outlet ports and the second positionplacing the conductance control structure in a location spaced away fromthe plurality of outlet ports. The at least one RF source can bemodulated to correspond to the first position and the second position ofthe conductance control structure. The gas flow into the plasmaprocessing volume can also be modulated to correspond to the firstposition and the second position of the conductance control structure.

Other aspects and advantages of the invention will become apparent fromthe following detailed description, taken in conjunction with theaccompanying drawings, illustrating by way of example the principles ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be readily understood by the followingdetailed description in conjunction with the accompanying drawings.

FIG. 1 is a side view of a simplified schematic drawing of a typicalnarrow gap plasma processing chamber.

FIGS. 2A and 2B are schematic diagrams of a small volume plasmaprocessing chamber system, in accordance with one embodiment of thepresent invention.

FIGS. 3A-3D are schematic diagrams of an alternative small volume plasmaprocessing chamber system, in accordance with one embodiment of thepresent invention.

FIG. 3E is a detailed cross-sectional view the conductance controlstructures and the plasma confinement structure, in accordance with oneembodiment of the present invention.

FIG. 3F is a detailed perspective view the conductance control structure302 and the plasma confinement structure, in accordance with oneembodiment of the present invention.

FIGS. 4A and 4B are schematic diagrams of an alternative small volumeplasma processing chamber system, in accordance with one embodiment ofthe present invention.

FIGS. 5A and 5B are simplified cross-sectional views of an alternativesmall volume plasma processing chamber system, in accordance with oneembodiment of the present invention.

FIGS. 5C and 5D are detailed views of a portion of the bottom facing orsubstantially horizontal portion of the plasma confinement structure inan alternative small volume plasma processing chamber system, inaccordance with one embodiment of the present invention.

FIGS. 5E-G are simplified cross-sectional views of an alternative smallvolume plasma processing chamber system, in accordance with oneembodiment of the present invention.

FIG. 6 is an exploded view of a conductance control structure, inaccordance with one embodiment of the present invention.

FIG. 7 is a flowchart diagram that illustrates the method operationsperformed in varying the pressure within the plasma processing volume,in accordance with embodiments of the present invention.

FIG. 8A is graphical representation of multiple pressure cycles withinthe plasma processing volume, in accordance with embodiments of thepresent invention.

FIG. 8B is detailed view of a portion of the graphical representation ofmultiple pressure cycles within the plasma processing volume, inaccordance with embodiments of the present invention.

FIG. 8C is a graph representation of the rate of pressure change, inaccordance with embodiments of the present invention.

FIGS. 9A-9F illustrate a pressure wave progression through the plasmaprocessing volume, in accordance with embodiments of the presentinvention.

FIG. 10 is a graphical representation of ion and neutral flux densities,in accordance with embodiments of the present invention.

FIG. 11A is a series of photos of prior art, constant pressure etchprocess results.

FIG. 11B compares the constant pressure etch process to a pulsedpressure etch process, in accordance with embodiments of the presentinvention.

FIG. 12A is a graph showing the relationship of pressure and lateraletching, in accordance with embodiments of the present invention.

FIG. 12B is a simplified schematic diagram of high aspect ratio contactfeatures, in accordance with embodiments of the present invention.

FIG. 13 is a simplified schematic diagram of a computer system inaccordance with embodiments of the present invention.

FIG. 14A is a graphical representation of the decay rates of electrons,ions, radicals, in accordance with embodiments of the present invention.

FIG. 14B is a graphical representation of multiple timing sequences ofpressure pulse and RF modulation, in accordance with embodiments of thepresent invention.

FIG. 15A is a graph of a gas only modulation, in accordance withembodiments of the present invention.

FIG. 15B is a graph of a gas and RF modulation, in accordance withembodiments of the present invention.

FIG. 16 is a detailed view of a portion of the graph of a gas and RFmodulation, in accordance with embodiments of the present invention.

FIG. 17 is a further detailed view of a portion of the graph of a gasand RF modulation, in accordance with embodiments of the presentinvention.

FIG. 18 is a flowchart diagram that illustrates the method operationsperformed in varying the pressure and modulating at least one RF sourcewithin the plasma processing volume, in accordance with embodiments ofthe present invention.

DETAILED DESCRIPTION

Several exemplary embodiments for a system, method and apparatus fordynamically changing and controlling the peripheral conductance of theprocess gases so as to induce a fast change in the pressure in theplasma processing volume will now be described. It will be apparent tothose skilled in the art that the present invention may be practicedwithout some or all of the specific details set forth herein.

One proposed system and method provides a small plasma processing volumedefined as the volume between the surface being processed, a top surfaceof a plasma confinement structure and an outer perimeter of the plasmaconfinement structure. One or more point of use gas conductance controlmechanisms near the outer perimeter of the plasma confinement structureenable localized, faster pressure changes within the plasma processingvolume than can be achieved by changing a pressure of the entire processchamber.

Introducing a gas conductance change at the peripheral conductance ofthe process gases and by-products can be achieved by producing a fastchange in the pressure in the plasma processing volume above the surfacebeing processed (e.g., a wafer surface). One approach controls the rateof gases (e.g., process gases and plasma byproducts) flow out of theplasma processing volume with a conductance control ring. An output flowthrough at least a portion of outlet ports in a plasma confinementstructure can be more restricted or less restricted varying betweensubstantially completely restricted flow to substantially fullyunrestricted flow by a conductance control ring to vary the pressurewithin the plasma processing volume above the wafer. The more or lessrestriction of the outlet ports in the plasma confinement structure canbe performed by a shifting, moving or rotating at least a portion of theconductance control ring located near or around a set of outlet ports ina perimeter of the plasma confinement structure.

A conductance profile can be selected with a shifting, moving orrotating speed profile of the conductance control ring. A controlledmotion of the conductance control ring can be linear or rotational withrespect to the outlet ports in the perimeter of the plasma confinementstructure. A time profile of the control motion of the conductancecontrol ring can provide a corresponding pressure modulation within theplasma processing volume relative to time.

Variations in pressure in the plasma processing volume can vary ormodulate several parameters including, ions to neutral ratio, ionenergy, IEDF and IADF. At low pressure there is less collision betweenthe ions entering the plasma sheath (voltage drop) above the wafersurface. Reducing ion collisions causes more of the ions to exit theplasma sheath in a substantially perpendicular direction to the plasmasheath and to the surface of the substrate being processed. As a result,reducing the ion collisions improves the directionality of the ionsentering any features present in the surface of the substrate beingprocessed.

Further, as the pressure changes the effective plasma density as well anarea ratio changes. Changing the effective plasma density and/or thearea ratio also changes the ion energy distribution function (IEDF) froma low ion energy ratio to a high ion energy ratio. The ion energydistribution function can be adjusted to affect the plasma processingperformance of the process within the plasma processing volume.

By way of example, a precise control of ion to neutral flux is oneimportant operational parameter used to maintain a good mask profileduring etch. A good mask profile during etch directly impacts thequality of the final etch profile.

A fast pressure pulse in the plasma processing volume can also besynchronized with RF power delivery and/or process gas chemistrymodulation and/or wafer temperature profile to further enhance thedesired control of ion to neutral flux along with difference processchemistry, to meet the requirement of next generation etch processes. Apressure pulse within the plasma processing volume can also provide aplasma chemistry control to the feature being etched and thus provideimproved selectivity, profile control and radial uniformity.

FIGS. 2A and 2B are schematic diagrams of a small volume plasmaprocessing chamber system 200, in accordance with one embodiment of thepresent invention. The small volume plasma processing chamber system 200includes a processing chamber 201, one or more gas sources 102, one ormore RF sources 117A, 117B and a controller 119 coupled to theprocessing chamber and the gas sources. The processing chamber 201 isdefined by inner walls 201A-D and includes a substrate support 106 forsupporting a substrate 101.

The processing chamber 201 also includes a plasma processing volume 110.The plasma processing volume 110 is defined by an inner surface 108A ofthe top 108 of the plasma processing chamber (e.g., a surface of a topelectrode coupled to RF source 117B), the surface 106A, 106B of thesubstrate support 106 (e.g., a bottom electrode coupled to RF source117A), if the substrate 101 is not present, and the surface 106A and thesurface 101A of the substrate 101, when the substrate is present. Theplasma processing volume 110 is typically less than about 10 percent ofthe total volume of the processing chamber 201. A plasma confinementstructure 114 defines an outer perimeter of the plasma processing volume110.

The plasma confinement structure 114 includes multiple outlet ports 116.A positioning actuator 207 is coupled to the conductance controlstructure 202 to apply a desired level of restriction to the outletports 116. The outlet ports 116 can be substantially fully restricted tominimize gas output flow through the outlet ports, as shown in FIG. 2A,by a conductance control structure 202 being placed immediately adjacentto the outlet ports 116. The restricted outlet ports 116 restrict theflow of the process gases and plasma byproducts out of the plasmaprocessing volume 110 and thus generates an increased pressure withinthe limited volume of only the plasma processing volume 110.

When the outlet ports 116 are restricted, the pressure within the plasmaprocessing volume 110 can increase at a rate of up to about 20 mtorr per100 ms. In many plasma processes a relatively small pressure increase inthe plasma processing volume 110, as little as about 5 mtorr pressure,can be a sufficient pressure change to create the desired effects. Therestricted outlet ports 116 can generate an increased pressure withinthe plasma processing volume 110 of about 50 mtorr or greater, with moretime is allowed.

By way of example, if only 5 mtorr pressure increase is desired, thenthe outlet ports 116 may only need to be restricted for about 25 ms,which is about 25 percent of the time required to increase the pressure20 mtorr, within the plasma processing volume 110. Alternatively, if a40 mtorr pressure increase is desired, then the outlet ports 116 mayneed to be restricted about 200 ms, which is about 200 percent of thetime required to increase the pressure 20 mtorr, within the plasmaprocessing volume 110.

Alternatively, as shown in FIG. 2B, the outlet ports 116 can besubstantially fully unrestricted when the positioning actuator 207,moves the conductance control structure 202 a sufficient distance Δ1away from the outlet ports 116, where distance Δ1 is between about 0.25mm to about 25 mm (i.e., between about 0.01 inches and about 1.0 inches)and more specifically between about 0.25 mm to about 12.5 mm (i.e.,between about 0.01 inches and about 0.5 inches).

The substantially fully unrestricted outlet ports 116 can more freelyallow the flow of the process gases and plasma byproducts toward thevacuum pumps 118. When substantially fully unrestricted, the outletports 116 can generate a pressure decrease within the plasma processingvolume 110 of a rate of up to about 20 mtorr per 100 ms. The conductancecontrol structure 202 can be moved any desired more or less thandistance Δ1 away from the outlet ports 116 to provide a correspondingselected amount of restriction to the outlet flow through the outletports.

Modulating the amount of restriction of the outlet flow of the outletports 116 can be used to correspondingly modulate an increase and adecrease of the pressure within only the plasma processing volume 110 ata rate of about 10 Hz. The pressure in the remainder of the processingchamber 201, external of the plasma processing volume 110, remainssubstantially constant while the pressure within the plasma processingvolume is varied.

It should be understood that the above examples are mere exemplaryembodiments and different structures of and control schemes of theconductance control structure 202 and the plasma confinement structure114 will have correspondingly different pressure rate increases anddecreases within the plasma processing volume 110 to correspond with theopening and closing of the ports 116.

FIGS. 3A-3D are schematic diagrams of an alternative small volume plasmaprocessing chamber system 300, in accordance with one embodiment of thepresent invention. The small volume plasma processing chamber system 300is substantially similar to the small volume plasma processing chambersystem 200 described in FIGS. 2A and 2B, above. The primary differenceis the multiple outlet ports 116′ are moved to the outer periphery ofthe plasma confinement structure 114. Correspondingly, the conductancecontrol structure 302 is placed in a location proximate to the outletports 116′.

Operationally, the small volume plasma processing chamber system 300 issubstantially similar to the small volume plasma processing chambersystem 200. By way of example, moving the conductance control structure302 selects an amount of restriction to the outlet flow through theoutlet ports 116′ and correspondingly modulates the pressure within theplasma processing volume 110. As shown in FIG. 3A, the conductancecontrol structure 302 substantially fully restricted the outlet flowthrough the outlet ports 116′. As shown in FIG. 3B, the conductancecontrol structure 302 is shifted vertically in a direction 304A topartially un-restrict and partially restrict the outlet flow through theoutlet ports 116′.

As shown in FIG. 3C, the conductance control structure 302 is shiftedvertically in a direction 304A to substantially fully un-restrict theoutlet flow through the outlet ports 116′. As shown in FIG. 3D, theconductance control structure 302 is shifted horizontally a distance Δ2in a direction 304C to create openings 316 so as to reduce therestriction to the outlet flow through the outlet ports 116′.

FIG. 3E is a detailed cross-sectional view the conductance controlstructures 202 and 302 and the plasma confinement structure 114, inaccordance with one embodiment of the present invention. The plasmaconfinement structure 114 includes many outlet ports 116 in the bottomfacing portion 114A and many outlet ports 116′ in the peripheral portion114B. The conductance control structures 202 and 302 are coupled to thepositioning actuator 207 and can be moved close to the outlet ports 116,116′, as shown, to restrict the outlet flow through the outlet ports oraway from the outlet ports to substantially fully un-restrict the outletflow through the outlet ports as shown in the previously discussed FIGS.2A-3D.

FIG. 3F is a detailed perspective view the conductance control structure302 and the plasma confinement structure 114, in accordance with oneembodiment of the present invention. The plasma confinement structure114 includes many radial slot shaped outlet ports 116 in the bottomfacing portion 114A. The slot shaped outlet ports 116 extend outwardfrom the interior portion 114A′ toward the peripheral portion 114B.

FIGS. 4A and 4B are schematic diagrams of an alternative small volumeplasma processing chamber system 400, in accordance with one embodimentof the present invention. The small volume plasma processing chambersystem 400 is substantially similar to the small volume plasmaprocessing chamber system 200 described in FIGS. 2A and 2B, above. Theprimary difference is the multiple outlet ports 116′ are formed betweencorresponding plasma confinement rings 402 in the peripheral portion114B of the plasma confinement structure 114. The plasma confinementrings 402 are shown collapsed together or closed in FIG. 4A, thus withthe outlet ports 116′ being substantially fully restricted or closed.

Operationally, the small volume plasma processing chamber system 400 issubstantially similar to the small volume plasma processing chambersystem 200. By way of example, separating the plasma confinement rings402 reduces the restriction the outlet flow through the outlet ports116′ as a width W1 of the outlet ports is increased. Separating andcollapsing the plasma confinement rings 402 in respective direction404A, 404B can correspondingly modulate the pressure within the plasmaprocessing volume 110.

FIGS. 5A and 5B are simplified cross-sectional views of an alternativesmall volume plasma processing chamber system 500, in accordance withone embodiment of the present invention. FIGS. 5C and 5D are detailedviews of a portion of the bottom facing or substantially horizontalportion 114A of the plasma confinement structure 114 in an alternativesmall volume plasma processing chamber system 500, in accordance withone embodiment of the present invention.

The small volume plasma processing chamber system 500 is substantiallysimilar to the small volume plasma processing chamber system 200described in FIGS. 2A and 2B, above. The primary difference isrestriction of the outlet flow through the multiple outlet ports 116 isincreased and decreased by shifting the conductance control structure202″ in a rotational direction 504A or 504B to align or partially alignthe outlet ports 116 with the corresponding openings 516 in theconductance control structure.

The positioning actuator 207′ can move or shift or rotate theconductance control structure 202″ in rotational directions 504A and504B. As shown in FIGS. 5A and 5C, the outlet ports 116 are not alignedthe corresponding openings 516 in the conductance control structure andthus the outlet flow through the ports is substantially fullyrestricted. As shown in FIGS. 5B and 5D, the outlet ports 116 arealigned the corresponding openings 516 in the conductance controlstructure and thus the outlet ports are open and substantially fullyunrestricted. It should be understood that the outlet ports 116 can bepartially aligned with the corresponding openings 516 in the conductancecontrol structure and thus the outlet flow through the outlet ports canbe adjusted between substantially fully unrestricted and substantiallyfully restricted.

FIGS. 5E-G are simplified cross-sectional views of an alternative smallvolume plasma processing chamber system 550, in accordance with oneembodiment of the present invention. The small volume plasma processingchamber system 550 is substantially similar to the small volume plasmaprocessing chamber system 500 described in FIG. 5A-D, above. The primarydifference is that the outlet flow through only a portion of themultiple outlet ports 116, 116′, 116″, 116′ are restricted orunrestricted at any one time and thus allowing an asymmetrical theoutlet flow operation.

By way of example, as shown in FIG. 5E all of the outlet ports 116,116′, 116″, 116′ are substantially fully restricted. The openings 516 inthe conductance control structure 202″ are shown offset in phantombecause the openings are not aligned with the outlet ports 116.

Referring to FIG. 5F, the openings 516 are shifted to align with outletports 116 and thus only the outlet flow through the outlet ports 116 aresubstantially fully unrestricted, while the outlet flow through theremaining outlet ports 116′, 116″, 116′ remains substantially fullyrestricted. When only the outlet flow through the outlet ports 116 issubstantially unrestricted, the process gases and plasma byproducts canflow in directions 502 toward the outlet ports 116. The process gasesand plasma byproducts do not flow in directions 502′, 502″, 502′ becausethe outlet flow through the corresponding ports 116′, 116″, 116′ aresubstantially fully restricted.

Referring to FIG. 5G, the openings 516 are shifted to align with outletports 116′ and thus only the outlet flow through the outlet ports 116′are substantially fully unrestricted, while the remaining outlet ports116, 116″, 116′ remain substantially fully restricted. When only theoutlet ports 116′ have the outlet flow unrestricted, the process gasesand plasma byproducts can flow in directions 502′ toward theunrestricted outlet ports 116′. The process gases and plasma byproductscannot flow in directions 502, 502″, 502′ because the correspondingoutlet ports 116, 116″, 116′ are substantially fully restricted.

The conductance control structure 202 can be further shifted to openselected outlet ports 116, 116′, 116″, 116′. It should be understoodthat while each portion of the outlet ports 116, 116′, 116″, 116′corresponds to approximately a quadrant of the plasma confinementstructure 114, it should be understood that the number, shape andplacement of the openings 516 in the conductance control structure 202can be selected to restrict or un-restrict the outlet flow through asfew as a single one of the outlet ports 116, 116′, 116″, 116′.

Controlling the outlet flow through only a selected portion of theoutlet ports 116, 116′, 116″, 116′ allows the system 550 toasymmetrically and directionally select the flow of the plasma and theprocessing gases across the surface of the wafer 101 being processed. Byway of example, if greater concentration of plasma processing weredesired in the area of the surface of the wafer corresponding to outletports 116″, then the concentration of the process gases can be increasedand input to the plasma processing volume 110 and with the outlet flowthrough the outlet ports 116″ substantially fully unrestricted to causethe flow in directions 502″. Similarly, the concentration of the processgases can be decreased and input to the plasma processing volume 110 andwith the outlet ports 116″ substantially fully restricted to cause theflow in directions 502″ to reduce the plasma processing rate in the areaof the surface of the wafer corresponding to outlet ports 116″.

Opening only a selected portion of the outlet ports 116, 116′, 116″,116′″ also allows for an asymmetrical, non-radial distribution of thepressure and concentration of the process gases, plasma and byproducts.The non-radial distribution can be manipulated to minimize some of theradial plasma processing non-uniformity effects that are common inplasma processing chambers.

FIG. 6 is an exploded view of a conductance control structure 602, inaccordance with one embodiment of the present invention. The conductancecontrol structure 602 is somewhat similar to the conductance controlstructure 202 described above, however the outlet ports 116′ are formedin the substantially vertical outer periphery 114B of the plasmaconfinement structure 114. The conductance control structure 602includes at least some openings 616 in a corresponding, substantiallyvertical portion 602B.

The conductance control structure 602 has a diameter D1 that is slightlywider than a diameter D2 of the plasma confinement structure 114. Inoperation, the plasma confinement structure 114 will be nested withinthe conductance control structure 602. The conductance control structure602 can be rotated or shifted in directions 604A and 604B by thepositioning actuator 207′ to align at least one of the openings 616 toat least one of the outlet ports 116′ to increase or decrease therestriction to the outlet flow through the outlet port.

While openings 616 are shown substantially evenly distributed around theconductance control structure 602, it should be understood that theopenings 616 may be unevenly distributed around the conductance controlstructure 602. Alternatively, the openings 616 may only be included inone or more radial portions 618A, 618B or segments of the periphery ofthe conductance control structure 602, similar to the plasma processingchamber system 550 described in FIGS. 5E-5G above and thus provide anasymmetrical and directional selection of the flow of the plasma and theprocessing gases across the surface of the wafer 101 being processed.

It should also be understood that the conductance control structure 602can also include openings 616 in the substantially horizontal portion602A. The openings 616 in the substantially horizontal portion 602Acorrespond to outlet ports 116 in the substantially horizontal portion114A of the plasma confinement structure 114 as described in thepreceding figures.

FIG. 7 is a flowchart diagram that illustrates the method operations 700performed in varying the pressure within the plasma processing volume110, in accordance with embodiments of the present invention. In anoperation 705, the outlet flow through at least one outlet port 116,116′ in the plasma confinement structure 114 is substantially fullyunrestricted. The outlet flow through the least one port outlet 116,116′ in the plasma confinement structure 114 can be substantially fullyunrestricted by moving the corresponding conductance control structure202, 302, 402, 202″, 602 so as to align the at least one outlet portwith or create corresponding openings 216, 316, 516 and/or 616.

In an operation 710, one or more processing gases are injected into theplasma processing volume 110. In an operation 715, the process gasesflow in at least one substantially radial direction 112 through theplasma processing volume 110 toward one or more outlet ports 116, 116′in the plasma confinement structure 114 at the periphery of the plasmaprocessing volume.

In an operation 720, a plasma is formed in the plasma processing volume110 by applying an RF signal to at least one of the top electrode 108 orthe substrate support 106 (e.g. bottom electrode) from the respective RFsources 117B, 117A. The flow of the process gases distribute the ions,radicals and neutrals generated by the plasma.

In an operation 725, the pressure is increased in the plasma processingvolume 110. The pressure in the plasma processing volume 110 can beincreased by substantially fully restricting the outlet flow throughleast a portion of the at least one outlet port 116, 116′. The outletflow through the at least one outlet port 116, 116′ can be substantiallyfully restricted by shifting the conductance control structure 202, 302,402, 202″, 602 to restrict or block the at least one outlet port asshown in the figures above.

The pressure in the plasma processing volume 110 can increase at a rateof up to about 30 mtorr/100 ms. The amount of pressure increase can alsobe controlled by varying the flowrate of the process gases from theprocess gas sources 102 into the plasma processing volume 110.

As discussed above, as little as about 5 mtorr pressure change, eitheran increase or a decrease, can make significant process variations dueto the corresponding changes in the plasma chemistries. By way ofexample, as the pressure changes in the plasma processing volume 110,the ratio of ions, radicals and neutrals and the plasma density varies.

As the pressure reaches a desired set point, one or both of the RFsources 117A, 117B can optionally remain constant, be modulated,reduced, enabled or disabled operational state to also allow furtherselection of the ratios of ions, radicals and neutral species in theplasma.

In an operation 730, the pressure is decreased in the plasma processingvolume 110. The pressure in the plasma processing volume 110 can bedecreased by reducing the restriction of the outlet flow through atleast a portion of the outlet ports 116, 116′. The outlet flow throughthe outlet ports 116, 116′ can be increased (e.g., less restricted) byshifting the conductance control structure 202, 302, 402, 202″ 602 toalign or create openings to correspond to the outlet ports 116, 116′.Reducing the restriction of the outlet flow through the outlet ports116, 116′ allows the process gases and the plasma byproducts to rushtoward the outlet ports and the outlets, e.g., vacuum pumps, of theplasma processing chamber 201. The pressure in the plasma processingvolume 110 can decrease at a rate of up to about 20 mtorr/100 ms. Therate of change of the pressure can be selected from between about 1mtorr/100 ms to about 20 mtorr/100 ms with movement of the conductancecontrol structure. For a rotary type configuration such as shown inFIGS. 3F and 5A-6, the conductance change could be even faster than 20mtorr/100 ms. Reducing the pressure in the plasma processing volume 110moves plasma byproducts away from a center region 120 of plasmaprocessing volume. As a result, some radial non-uniformity effects ofthe plasma processing can be reduced or eliminated.

As described above, an asymmetrical flow of the processing gases usesthe non-uniform nature of asymmetrical venting, e.g., substantiallyfully unrestricted outlet flow through only a selected portion orsegment of the outlet ports 116, 116′, can vary the etch rate in acorresponding asymmetrical pattern. The asymmetrical outlet flow throughoutlet ports can be selectively moved around the surface being processedto counteract radial non-uniformities.

As the pressure reaches a desired set point, one or both of the RFsources 117A, 117B can optionally remain constant, be modulated,reduced, enabled or disabled operational state to further select orcontrol the ratios of ions, radicals and neutral species in the plasma.

In an operation 735, the method operations can end if no additionalpressure cycles are required in the plasma processing volume 110.Alternatively, if additional pressure cycles are required in the plasmaprocessing volume 110 then the method operations can continue in anoperation 725 above.

FIG. 8A is graphical representation 800 of multiple pressure cycleswithin the plasma processing volume 110, in accordance with embodimentsof the present invention. FIG. 8B is detailed view of a portion 830 ofthe graphical representation 800 of multiple pressure cycles within theplasma processing volume 110, in accordance with embodiments of thepresent invention. As described above, the pressure within the plasmaprocessing volume 110 can be varied at a rate of about 10 Hz or more,depending on the desired pressure change and the possible rate ofpressure change. Each cycle of the pressure change can be accomplishedby a cycle of closing the ports 116, 116′ and opening the ports. Theconductance control structure 202, 302, 402, 202″ 602 of the variousembodiments described above can be cycled through the port 116, 116′substantially fully unrestricted position and substantially fullyrestricted position and various positions between fully restricted andfully unrestricted to provide the desired cycle of the pressure change.By way of example, the positioning actuator 207 can alternate theconductance control structure 202 in directions 204A and 204B.Similarly, conductance control structures 202″ and 602 can be rotated orstepped at a substantially continuous rate to provide the desired cycleand rate of the pressure change in the plasma processing volume 110. Theflow rate of the process gases from the process gas source 102 into theplasma processing volume 110 can also be selected to increase ordecrease the pressure within the plasma processing volume.

Referring to FIGS. 8A and 8B, a control signal graph 810 is shownsuperimposed to a pressure graph 820 of the pressure within the plasmaprocessing volume 110. The control signal graph 810 shows the controlsignals to increase and decrease restriction on the outlet flow throughthe outlet ports 116, 116′. Time in seconds is shown across thehorizontal axis. At time of about 3.15 sec, the control signalsubstantially fully restricts the outlet flow through the outlet ports116, 116′. At about time 3.2 sec, the pressure begins a gradual increasefrom about 20 mtorr to about 90 mtorr at time 3.3 sec.

Referring to FIG. 8B, time in seconds is shown across the horizontalaxis. At end of 32^(nd) second the pressure begins to change from 20 mTand at end of 33^(rd) second, the pressure has risen to about 90 mT.This pressure change is 70 mT/1 sec or 70 mT/1000 ms. FIG. 8B shows atime delay error due to lack of fast pressure measurement instruments.However, the actual pressure change is proportional to change inconductance control structure position, such that the actual rate ofchange in pressure is about 70 mT/500 ms as is graphed in FIG. 8C.

The pressure is maintained at about 90 mtorr. At a time of about 33.6sec the control signal switches to reduce the restriction on the outletflow through the outlet ports 116, 116′. At a time of about 33.7 sec,the pressure begins to decrease to arrive at about 20 mtorr at a time ofabout 35 sec. The pressure stabilizes at about 20 mtorr until thecontrol signal increases the restriction on the outlet flow through theoutlet ports 116, 116′ at time about 36 sec. The cycle then repeats.

FIG. 8C is a graph representation 850 of the rate of pressure change, inaccordance with embodiments of the present invention. As shown the rateof pressure change in the plasma processing volume 110 is about 17 mtorrper 100 msec. Thus allowing up to about a 17 mtorr pressure change cycleat a rate of about 10 Hz.

FIGS. 9A-9F illustrate a pressure wave progression through the plasmaprocessing volume 110, in accordance with embodiments of the presentinvention. Beginning with FIG. 9A, the plasma processing volume 110 ispressurized to an increased pressure because the outlet flow through theoutlet ports 116 is closed. The outlet flow through the outlet ports 116has been sufficiently restricted for a time sufficient to pressurize theplasma processing volume 110 substantially uniformly such that eachrespective portion 120, 122, 124, 126 of the plasma processing volumehas an equal pressure.

At a time T1, when the outlet flow through the outlet ports 116 issubstantially fully unrestricted, as shown in FIG. 9B, the process gasesand byproducts are pushed away from the central portion 120 and towardthe outlet ports as the pressure in the outermost portions 126 of theplasma processing volume 110 is reduced to substantially the samepressure as the remainder of the processing chamber 201, external fromthe plasma processing volume. The pressure in portions 124 is slightlyreduced.

At a time T2, a short time after T1, as shown in FIG. 9C, more of theprocess gases and byproducts are pushed away from the central portion120 and toward the outlet ports. The pressure in portions 122 and 124are each slightly reduced.

At a time T3, a short time after T2, as shown in FIG. 9D, more of theprocess gases and byproducts are pushed away from the central portion120 and toward the outlet ports. The pressure in portions 120, 122 and124 are each slightly reduced.

At a time T4, a short time after T3, as shown in FIG. 9E, more of theprocess gases and byproducts are pushed away from the central portion120 and toward the outlet ports. The pressure in portions 120, 122 and124 are each again slightly reduced.

At a time T5, a short time after T4, as shown in FIG. 9F, more of theprocess gases and byproducts are pushed away from the central portion120 and toward the outlet ports. The pressure in portions 120, 122 and124 of the plasma processing volume 110 are reduced to substantially thesame pressure as the remainder of the processing chamber 201 externalfrom the plasma processing volume.

Pressure changes in the plasma processing volume 110 determine theratios of ions, radicals and neutral species in the plasma. FIG. 10 is agraphical representation 1000 of ion and neutral flux densities, inaccordance with embodiments of the present invention. The ion fluxdensity graph 1010 is a substantially constant density, e.g., about 4.5,over a range of pressures between about 2 and about 20 mtorr. Theneutral flux density graph 1020 varies widely from a density less thanabout 1×10¹⁴ to more than about 6.5×10¹⁴. The neutral flux densityincreases substantially linearly with pressure.

As shown in FIG. 10, a variation from 5 mtorr to 15 mtorr would havesubstantially the same ion flux density. In contrast, the neutral fluxdensity would vary from about 1 to about 4, i.e., a factor of 4 timesthe density at the 15 mtorr, higher pressure, as compared to the 5 mtorrlower pressure. As a result, this 10 mtorr manipulation or modulation ofthe pressure gives a only limited selection of the ion flux densitywhile at the same time gives broad selection to the neutral fluxdensity. The etching performance of the different ratios can then beselected by the corresponding pressure of the plasma processing volume110.

FIG. 11A is a series of photos of prior art, constant pressure etchprocess results. The first view 1110 is a first etch process executed ata constant 12 mtorr. Each of the features 1112 has a tapered shape withthe lower portion of the feature coming almost to a point when a wider,flatter bottom portion would be a much preferred result. A detailed view1114 shows an acceptable profile in the mid depth of the feature. Apreferred feature profile would have the acceptable profile of the middepth (e.g., smooth, parallel sides) of the feature throughout the fulldepth of the feature.

The second view 1120 is a second etch process executed at a constant 40mtorr. Each of the features 1122 has a less tapered shape than thefeatures 1112, however undesirable striation type non-uniformities areformed in the mid depth profile 1124. The third view 1130 is a thirdetch process executed at a constant 70 mtorr. Each of the features 1132has a tapered shape similar to the features 1112, however undesirablestriation type non-uniformities are also formed in the mid depth profile1134.

FIG. 11B compares the constant pressure etch process 1120 to a pulsedpressure etch process 1150, in accordance with embodiments of thepresent invention. The pulsed pressure etch process 1150 varies the etchpressure within the plasma processing volume 110 from between about 12mtorr and about 70 mtorr. The pulsed pressure etch process 1150 yieldsan improved profile similar to the 40 mtorr constant pressure etchprocess 1120 but also eliminates the undesirable striations as shown inthe details view 1154 and further squares off the lower portions of thefeatures 1152.

FIG. 12A is a graph 1200 showing the relationship of pressure andlateral etching, in accordance with embodiments of the presentinvention. FIG. 12B is a simplified schematic diagram 1250 of highaspect ratio contact features, in accordance with embodiments of thepresent invention. In an etch process to form a high aspect ratiocontact (HARC), such as for a DRAM device, as the critical dimension(i.e., width Fw of the features F1, F2) becomes smaller and the pitch Pbetween the features F1, F2 is decreased (i.e., features are moreclosely spaced), an undesirable lateral etch can occur near the openingor top end of the features.

The lateral etch etches into the sidewalls of the features F1, F2 toform a bowed sidewall 1260. If the lateral etch occurs too quickly, thenthe bowed sidewall 1260 can form a hole in the area 1262 between theadjacent features F1 and F2 and thus result in a short circuit betweenthe two adjacent features. Therefore, the lateral etching needs to beminimized while also improving the bottom profile and depth Fd1 of thefeature F1 as compared to the lesser depth Fd2 of feature F2.

The graph 1200 as shown in FIG. 12A illustrates the effect of theoperating pressure and the sidewall bowing 1260 and the depth andprofile of the lower end of the features F1, F2. At lower pressures,fewer ions 1252, 1254 deflect off other ions due to the reduce densityof ions present in the lower pressure. Thus, at lower pressures thedirectionality of the ions 1252, 1254 entering the features F1, F2 isimproved and more ions reach the bottom of the feature to perform thedesired directional etch. Further, as more ions 1252, 1254 enter thefeatures, less ions deflect off the mask layer 1256 to impinge on thesidewall to produce the sidewall bowing 1260 (e.g., undesirable lateraletch)

During the etch process, polymer species (e.g., fluorocarbon orhydrocarbon based depending on the etch process chemistry used) may beproduced. The polymer species have a high sticking coefficient and tendto build up as polymer deposits 1270 near the top or opening of thefeatures F1, F2. In a selected etching chemistry the polymer deposits1270 have a low sticking coefficient and thus do not adhere to the sidesof feature F1. Increasing the temperature of the substrate 101 can alsoreduce the surface mobility and thus substantially prevent the formationof the polymer deposits 1270. High energy ions from the plasma can alsoremove the polymer deposits 1270. Yet another way to remove the polymerdeposits 1270 is to perform an oxygen or fluorine radical etch such asby injecting O2 or NF3, respectively between the main etch processes.

FIG. 13 is a simplified schematic diagram of a computer system 1300 inaccordance with embodiments of the present invention. The computersystem 1300 is an exemplary computer system such as may be included inthe controller 119 described above. It should be appreciated that themethods described herein may be performed with a digital processingsystem, such as a conventional, general-purpose computer system. Specialpurpose computers, which are designed or programmed to perform only onefunction, may be used in the alternative. The computer system includes acentral processing unit (CPU) 1304, which is coupled through bus 1310 torandom access memory (RAM) 1328, read-only memory (ROM) 1312, and massstorage device 1314. Phase control program 1308 resides in random accessmemory (RAM) 1328, but can also reside in mass storage 1314 or ROM 1312.

Mass storage device 1314 represents a persistent data storage devicesuch as a floppy disc drive or a fixed disc drive, which may be local orremote. Network interface 1330 provides connections via network 1332,allowing communications with other devices. It should be appreciatedthat CPU 1304 may be embodied in a general-purpose processor, a specialpurpose processor, or a specially programmed logic device. Input/Output(I/O) interface provides communication with different peripherals and isconnected with CPU 1304, RAM 1328, ROM 1312, and mass storage device1314, through bus 1310. Sample peripherals include display 1318,keyboard 1322, cursor control 1324, removable media device 1334, etc.

Display 1318 is configured to display the user interfaces describedherein. Keyboard 1322, cursor control 1324, removable media device 1334,and other peripherals are coupled to I/O interface 1320 in order tocommunicate information in command selections to CPU 1304. It should beappreciated that data to and from external devices may be communicatedthrough I/O interface 1320. The embodiments can also be practiced indistributed computing environments where tasks are performed by remoteprocessing devices that are linked through a wire-based or wirelessnetwork.

Synchronizing Pressure Change and Bias Change

Changing the pressure of the plasma processing volume 110 can manipulatethe ratios of electrons, ions, radicals and neutrals as described above.Modulating (i.e., varying power between 0 and full power) the one ormore RF sources 117A, 117B can also manipulate the ratios of electrons,ions, radicals over time. FIG. 14A is a graphical representation 1400 ofthe decay rates of electrons, ions, radicals, in accordance withembodiments of the present invention. At a time T0, the one or more RFsources 117A, 117B are in a steady state and the respective levels ofelectrons 1402, ions 1404, and radicals 1406 are shown. The graphicalrepresentation 1400 is not shown to scale as the levels of the electrons1402, ions 1404, and radicals 1406 in a given process recipe may or maynot be in the levels relative to each other as shown. It should also benoted that the time scale shown is not linear as indicated by the breaksin the horizontal axis.

At a time T1, one or more of the RF sources 117A, 117B are modulated.For simplification of the explanation, the modulated RF sources 117A,117B are reduced to near zero output power but it should be understoodthat the output power can be reduced to some value between the value attime T0 and zero output power.

The quantity of electrons 1402 present in the plasma processing volume110 decays from the steady state level 1402A to near zero at a timeT1+about 50 microseconds. The quantity of ions 1404 present in theplasma processing volume 110 decays at a much slower rate, approachingzero at a time T1+about 200 microseconds. The quantity of radicals 1406present in the plasma processing volume 110 decays at a still slowerrate, approaching zero at a time T1+about 500 microseconds or more.

As a result of the different decay rates the reactive specie varies overtime. By way of example, at a time T0 steady state levels 1402A, 1404A,1406A are shown. At a time T2, some time after T1+about 50 microseconds,substantially all of the electrons 1402 are gone and yet the quantity ofions 1404 and radicals 1406 is substantially equal to the respectivesteady state levels 1404A, 1406A. Similarly, at a time T3, some timeafter T1+about 200 microseconds, substantially all of the electrons 1402and all of the ions 1404 have decayed to about zero, yet the quantity ofradicals 1406 is still quite high and in some circumstances may besubstantially equal to the radical steady state level 1406A. As theratios of the reactive specie vary at times T0, T2 and T3, differentprocesses can be more effectively applied at the respective times T0, T2and T3.

Insert examples of different processes at time T0, T2 and T3.

FIG. 14B is a graphical representation of multiple timing sequences1420-1470 of pressure pulse and RF modulation, in accordance withembodiments of the present invention. In timing graph 1420, the RF powermodulation is approximately 180 degrees out of phase with process gasflow. As a result, at a time T1, the RF power is increased and theprocess gas flow is reduced. This timing graph 1420 can be termed 180degrees out of phase, with the RF power modulation synchronized with thegas flow modulation. The resulting optical emission trace 1422 shows anargon (800 nm wavelength) trace proportional to both concentration andRF power. These graph illustrate a synchronized RF power and process gasmodulation with a slight time offset due to instrumentation error.

In timing graph 1430, the RF power modulation is approximately 200degrees out of phase with process gas flow. As a result, at a time T1,the RF power is increased and an about 20 degree delay after T1, theprocess gas flow is reduced. This timing graph 1430 can be termed 180degrees out of phase, with the RF power modulation leading the gas flowmodulation. The resulting optical emission trace 1432 shows an argon(800 nm wavelength) trace proportional to both concentration and RFpower. Rising edge spikes indicate when the RF pulses are lagging thegas pulse. Falling edge spikes indicate when the RF pulses are leadingthe gas pulse. OES shows an actual transition time of a first processgas mixture to a second process gas mixture, while synchronizing with RFpulse and process gas pressure.

In timing graph 1440, the RF power modulation is approximately 160degrees out of phase with process gas flow. As a result, at a time about20 degrees before T1, the process gas flow is reduced, and at time T1,the RF power is increased. This timing graph 1440 can be termed 180degrees out of phase, with the gas flow modulation leading the RF powermodulation. The resulting optical emission trace 1442 shows an argon(800 nm wavelength) trace proportional to both concentration and RFpower. Rising edge spikes indicate when the RF pulses are lagging thegas pulse. Falling edge spikes indicate when the RF pulses are leadingthe gas pulse 1442.

In timing graph 1450, the RF power modulation is approximately in-phasewith process gas flow. As a result, at a time T1, the RF power isincreased and the process gas flow is increased. This timing graph 1450can be termed in-phase, with the RF power modulation synchronized withthe gas flow modulation. The resulting optical emission trace 1452 showsan oxygen (770 nm wavelength) trace proportional to both concentrationand RF power . . . .

In timing graph 1460, the RF power modulation is approximately 20degrees out of phase with process gas flow. As a result, at a time T1,the RF power is increased and at a time of T1 plus about 20 degrees, theprocess gas flow is increased. This timing graph 1460 can be termedin-phase, with the RF power modulation leading the gas flow modulation.The resulting optical emission trace 1462 shows an oxygen (770 nmwavelength) trace proportional to both concentration and RF power. Thesteps indicate when the RF pulses are not in synch with the gas pulse .. . .

In timing graph 1470, the RF power modulation is approximately negative20 degrees out of phase with process gas flow. As a result, at a time ofabout 20 degrees before T1, the process gas flow is increased and attime T1, the RF power is increased. This timing graph 1470 can be termedin-phase, with the gas flow modulation leading the RF power modulation.The resulting optical emission trace 1472 shows an oxygen (770 nmwavelength) trace proportional to both concentration and RF power. Thesteps indicate when the RF pulses are not in synch with the gas pulse.

FIG. 15A is a graph 1500 of a gas only modulation, in accordance withembodiments of the present invention. The graph 1500 includes a first RFgraph 1502 that can be at 27 or 60 MHz or similar high frequency. Thegraph 1500 also includes a second RF graph 1504 that can be at a lowerfrequency such as 2 MHz or similar low frequency. The pressure of theplasma processing volume 110 is shown in graph 1512. The opticalemission spectrum of the argon (800 nm wavelength) injection into theplasma processing volume 110 is shown in graph 1514. The opticalemission spectrum of the oxygen injection (770 nm wavelength) into theplasma processing volume 110 is shown in graph 1516. Since the RFsignals 1502, 1504 are not modulated, no spikes are indicated in the OESgraphs 1514, 1516.

FIG. 15B is a graph 1550 of a gas and RF modulation, in accordance withembodiments of the present invention. FIG. 16 is a detailed view of aportion 1600 of the graph 1550 of a gas and RF modulation, in accordancewith embodiments of the present invention. FIG. 17 is a further detailedview of a portion 1700 of the graph 1600 of a gas and RF modulation, inaccordance with embodiments of the present invention. Argon modulationgraph 1514 is 180 degrees out of phase with the modulation of RF2 1504,while the oxygen modulation graph 1512 is in-phase with the modulationof RF2. Rising edge spikes 1552 indicate the RF pulses are lagging thegas pulse. Falling edge spikes 1554 indicate when the RF pulses areleading the gas pulse. Coordinating variation of the gas and RFmodulation assists in the formation of high aspect ratio contacts(HARC), 3D, and NAND etch processes.

FIG. 18 is a flowchart diagram that illustrates the method operations1800 performed in varying the pressure and modulating at least one RFsource within the plasma processing volume 110, in accordance withembodiments of the present invention. In an operation 1805, the outletflow through at least one outlet port 116, 116′ in the plasmaconfinement structure 114 is substantially fully unrestricted. Theoutlet flow through the least one port outlet 116, 116′ in the plasmaconfinement structure 114 can be substantially fully unrestricted bymoving the corresponding conductance control structure 202, 302, 402,202″ 602 so as to align the at least one outlet port with or createcorresponding openings 216, 316, 516 and/or 616.

In an operation 1810, one or more processing gases are injected into theplasma processing volume 110. In an operation 1815, the process gases102 flow in at least one direction 112 through the plasma processingvolume 110 toward one or more outlet ports 116, 116′ in the plasmaconfinement structure 114 at the periphery of the plasma processingvolume.

In an operation 1820, a plasma is formed in the plasma processing volume110 by applying an RF signal to at least one of the top electrode 108 orthe substrate support 106 (e.g. bottom electrode) from the respective RFsources 117B, 117A. The flow of the process gases 102 distribute theions, radicals and neutrals generated by the plasma.

In an operation 1825, the pressure is increased in the plasma processingvolume 110. The pressure in the plasma processing volume 110 can beincreased by substantially fully restricting the outlet flow throughleast a portion of the at least one outlet port 116, 116′ as describedin more detail above.

As the pressure reaches a desired set point, one or both of the RFsources 117A, 117B can be modulated, reduced, enabled or disabledoperational state to also allow further selection of the ratios of ions,radicals and neutral species in the plasma in an operation 1830.

In an operation 1835, the pressure is decreased in the plasma processingvolume 110. The pressure in the plasma processing volume 110 can bedecreased by reducing the restriction of the outlet flow through atleast a portion of the outlet ports 116, 116′ as described in moredetail above.

As the pressure reaches a desired set point, one or both of the RFsources 117A, 117B can be modulated, reduced, enabled or disabledoperational state to further select or control the ratios of ions,radicals and neutral species in the plasma in an operation 1840.

In an operation 1845, the method operations can end if no additionalpressure and/or RF modulation cycles are required in the plasmaprocessing volume 110. Alternatively, if additional pressure cyclesand/or RF modulation are required in the plasma processing volume 110then the method operations can continue in an operation 1825 above.

With the above embodiments in mind, it should be understood that theinvention may employ various computer-implemented operations involvingdata stored in computer systems. These operations are those requiringphysical manipulation of physical quantities. Usually, though notnecessarily, these quantities take the form of electrical or magneticsignals capable of being stored, transferred, combined, compared, andotherwise manipulated. Further, the manipulations performed are oftenreferred to in terms, such as producing, identifying, determining, orcomparing.

Any of the operations described herein that form part of the inventionare useful machine operations. The invention also relates to a device oran apparatus for performing these operations. The apparatus may bespecially constructed for the required purpose, such as a specialpurpose computer. When defined as a special purpose computer, thecomputer can also perform other processing, program execution orroutines that are not part of the special purpose, while still beingcapable of operating for the special purpose. Alternatively, theoperations may be processed by a general purpose computer selectivelyactivated or configured by one or more computer programs stored in thecomputer memory, cache, or obtained over a network. When data isobtained over a network the data maybe processed by other computers onthe network, e.g., a cloud of computing resources. The embodiments ofthe present invention can also be defined as a machine that transformsdata from one state to another state. The transformed data can be savedto storage and then manipulated by a processor. The processor thustransforms the data from one thing to another. Still further, themethods can be processed by one or more machines or processors that canbe connected over a network. Each machine can transform data from onestate or thing to another, and can also process data, save data tostorage, transmit data over a network, display the result, orcommunicate the result to another machine.

The invention can also be embodied as computer readable code on acomputer readable medium or logic circuits. The computer readable mediumis any data storage device that can store data, which can thereafter beread by a computer system. Examples of the computer readable mediuminclude hard drives, network attached storage (NAS), read-only memory,random-access memory, CD-ROMs, CD-Rs, CD-RWs, DVDs, Flash, magnetictapes, and other optical and non-optical data storage devices. Thecomputer readable medium can also be distributed over a network coupledcomputer systems so that the computer readable code is stored andexecuted in a distributed fashion.

It will be further appreciated that the instructions represented by theoperations in the above figures are not required to be performed in theorder illustrated, and that all the processing represented by theoperations may not be necessary to practice the invention. Further, theprocesses described in any of the above figures can also be implementedin software stored in any one of or combinations of the RAM, the ROM, orthe hard disk drive.

Although the foregoing invention has been described in some detail forpurposes of clarity of understanding, it will be apparent that certainchanges and modifications may be practiced within the scope of theappended claims. Accordingly, the present embodiments are to beconsidered as illustrative and not restrictive, and the invention is notto be limited to the details given herein, but may be modified withinthe scope and equivalents of the appended claims.

What is claimed is:
 1. A plasma processing system comprising: aprocessing chamber; at least one gas source coupled to the processingchamber; a controller coupled to the processing chamber and the at leastone gas source; the processing chamber including: a top electrodedisposed within a top portion of the processing chamber; a substratesupport disposed opposite from the top electrode; a plasma processingvolume having a volume less than a volume of the processing chamber, theplasma processing volume being defined by: a surface of the topelectrode; a supporting surface of a substrate support opposing thesurface of the top electrode; and an outer perimeter defined by a plasmaconfinement structure, the plasma confinement structure including atleast one outlet port; at least one RF source coupled to at least one ofthe substrate support or the top electrode; and a conductance controlstructure movably disposed proximate to the at least one outlet port,wherein the conductance control structure restricts an outlet flowthrough the at least one outlet port when disposed in a first positionto a first flow rate and wherein the conductance control structureincreases the outlet flow through the at least one outlet port whendisposed in a second position to a second flow rate, wherein theconductance control structure moves between the first position and thesecond position corresponding to a selected processing state set by thecontroller during a plasma process and wherein the at least one RFsource is modulated corresponding to the selected processing state setby the controller during the plasma process.
 2. The system of claim 1,wherein the modulation of the at least one RF source is substantiallyin-phase with the selected processing state.
 3. The system of claim 1,wherein the modulation of the at least one RF source is substantially180 degrees out of phase with the selected processing state.
 4. Thesystem of claim 1, wherein the modulation of the at least one RF sourcelags the selected processing state.
 5. The system of claim 1, whereinthe modulation of the at least one RF source leads the selectedprocessing state.
 6. The system of claim 1, wherein the at least one RFsource includes a high frequency RF source having an output of about 27MHz.
 7. The system of claim 1, wherein the at least one RF sourceincludes a high frequency RF source having an output of about 60 MHz. 8.The system of claim 1, wherein the at least one RF source includes ahigh frequency RF source having an output of greater than about 27 MHzand low frequency RF source having an output of about 2 MHz.
 9. Thesystem of claim 1, wherein the controller coordinates an input flow rateof the at least one gas source into the processing volume withcoordination of the movement of the conductance control structure andthe modulation of the at least one RF source.
 10. The system of claim 1,wherein the at least one outlet port in the plasma confinement structureis formed in a substantially horizontal portion of the plasmaconfinement structure.
 11. The system of claim 1, wherein the at leastone outlet port in the plasma confinement structure is formed in asubstantially vertical portion of the plasma confinement structure. 12.A chamber, comprising, a substrate support; a top electrode; at leastone RF source coupled to at least one of the substrate support or thetop electrode; a confinement structure disposed to surround thesubstrate support, such that a plasma processing volume is definedbetween the substrate support, the top electrode and the confinementstructure, the confinement structure includes a plurality of outletports that surround the substrate support; and a conductance controlstructure disposed outside of the plasma processing volume and proximateto the plurality of outlet ports, the conductance control structurehaving a positioning actuator that provides movement of the conductancecontrol structure between a first position and a second position, thefirst position placing the conductance control structure immediatelyadjacent to the plurality of outlet ports and the second positionplacing the conductance control structure in a location spaced away fromthe plurality of outlet ports and wherein the at least one RF source ismodulated corresponding to the first position and the second position.13. The chamber of claim 12, further comprising: a controller, thecontroller being in communication with the positioning actuator todirect movement of the conductance control structure during one or moreprocess states of a plasma processing recipe.
 14. The chamber of claim13, wherein the controller being in communication with a gas source thatdirects processing gases into the plasma processing chamber during theplasma processing recipe, such that the controller adjusts theconductance control structure between the first position and the secondposition or between the first and second positions as defined by theplasma processing recipe.